Either way, Welcome!
The ESLClickFix is a resource for advice on points of English grammar and style, and a few other things.
If you're a student, and you've been asked to have a look at the advice here, click on the graphic below which matches the one on your corrections sheet. There you will find information that can help you improve in a focused area of grammar or style.
If you're a wayfarer, my best wishes that you find something useful!